This invention relates to television (TV) receiver apparatus comprising a video signal receiver and a global positioning system (GPS) signal receiver and to a related method.
At present, GPS is most notably associated with the Navigation System with Time and Ranging (NAVSTAR) GPS, an all weather, spaced based navigation system developed and operated by the US Department of Defense, although the general principles underlying GPS are universal and not merely limited to NAVSTAR. Accordingly, GPS hereafter refers to any global positioning system comprising a plurality of CDMA radio transmitters at different locations and a receiver which determines its location based on the time of arrival of the transmissions of the radio transmitters.
The general principles underlying GPS and methods and apparatus for its implementation are known. For example, see GPS Principles and Applications (Editor, Kaplan) ISBN 0-89006-793-7 Artech House, hereinafter xe2x80x9cKaplanxe2x80x9d.
With respect to TV receiver apparatus, it is known from U.S. Pat. No. 5,621,793 (Bednarek et al.), to provide a TV set top box with a GPS receiver whereby GPS enables the location of the TV set top box to be determined. Bednarek discloses using knowledge of the location of the GPS receiver and hence TV set top box in order to provide TV access control and to deter theft. For example, TV access control may be effected by receiving location information from the GPS receiver and, only when the present location is consistent with an authorised location, decrypting an incoming video signal to enable its display.
Recent progress in the field of GPS dedicated integrated circuit design has enabled the signal processing portion of GPS receivers to be produced relatively cheaply. However, invariably, a GPS receiver (whether integrated with TV receiver apparatus or not) is provided with a dedicated GPS antenna. Such antennas are considered necessary due to the very low signal strength of a GPS signal relative to background noise and especially where a signal is received from a satellite positioned at a shallow angle above the horizon relative to the receiver.
In the context of satellite video transmission, Bednarek contemplates a combined antenna arrangement (lines 28 to 35 of column 9) wherein the antenna is a small satellite dish and receives both GPS and communications signals from a combined GPS / communications orbiting satellite. However, as noted at lines 30 to 31 of column 9 of Bednarek, a disadvantage of such an antenna arrangement is that satellites usually do not combine GPS and communication functions. Furthermore, given that a GPS receiver is typically required to receive and track signals from at least four non-geostationary satellites in order to determine its location, it is not clear from Bednarek how using a single satellite dish antenna would work since satellite dishes have a narrow field of view.
It is an object of the invention to provide cheaper TV receiver apparatus comprising a TV signal receiver and a GPS signal receiver.
According to the present invention, TV receiver apparatus is provided comprising a video signal receiver for receiving video signals transmitted from an external, terrestrially based video signal transmitter, a GPS signal receiver for receiving GPS signals transmitted from an external GPS signal transmitter and signal coupling means connected to both receivers and adapted to provide both receivers with respective video and GPS signals via a common antenna.
Use of a common antenna obviates the need for a dedicated GPS antenna. Additionally, many households already possess an antenna, often an external Yagi antenna, adapted to receive terrestrially broadcasted signals and may be therefore readily connected to TV receiver apparatus according to the present invention, thereby reducing installation costs.
The apparatus may include an antenna adapted to optimally receive terrestrially broadcasted video signals and, in particular, those broadcasted at UHF or VHF bands.
For convenience, the TV receiver apparatus and the coupling means may be contained in a common housing, for example a television set-top box or a television with an integral receiver.
Also provided is a method of receiving video and GPS signals in TV receiver apparatus comprising a video signal receiver and a GPS signal receiver both connected via signal coupling means to a common antenna, ideally adapted to optimally receive UHF or VHF video signals. The method comprising the steps of (a) receiving, via the antenna, video signals in the video signal receiver from an external, terrestrially based video signal transmitter; and (b) receiving, via the antenna, GPS signals in the GPS signal receiver from an external GPS signal transmitter.